The implementation of `Keystore` requires a particular layout and naming
of keys. This is a rather strong limitation. Lift it and allow
specifying an arbitrary path for the secret and public key.
As it is possible to derive the public key from the secret key, make
the public key in `Keystore` optional. Also allow constructing
`MemorySigner` can now be initialized without a public key, by
deriving it.
When run with a secret and public key that do not cryptographically
match, `fn radicle_cli::terminal::io::signer` would prompt the user
for a password to unlock the secret key, and then carry on with a
mismatching key pair.
Fix this by verifying that the keys match in `MemorySigner::load`
and only swallow errors initializing the signer in cases where
prompting for a password makes sense. It does not make sense in the
case of mismatched keys.
Lorenz Leutgeb